They are quite punchy, and by no means a lesser option. They're nice and compact, therefore lighter, making them easier to lug around.
Fender amps have used a variety of different sized speakers since the 50s, but Marshall started the standard 12inch size with their JTM45 half stacks. It was what they could get at the time, and the legend was born.
Personally, I'm going to get a Fender-style 2x12 combo at some point as they sound lovely for cleans.